Solvent-based inkjet ink formulations

ABSTRACT

Solvent-based inkjet ink formulations including an organic solvent, a resin, a surfactant, and a colorant are provided. The inks have many desirable attributes such as extended decap time.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Utility application Ser. No.12/839,534, filed on Jul. 20, 2010, which claims priority to U.S.Provisional Application Ser. No. 61/227,007, filed on Jul. 20, 2009. Theentire contents of the foregoing applications are hereby incorporated byreference.

TECHNICAL FIELD

This disclosure relates to solvent-based inkjet ink formulations,products that include such formulations, and to methods of making andusing the same.

BACKGROUND

Inkjet printing typically involves ejecting inks from a component of aninkjet printer (e.g., from one or more nozzles of a printhead) onto asubstrate.

Inkjet printhead nozzles can be designed to operate within specificviscosity ranges of inks and initial evaporation can generally cause anincrease in viscosity that affects the ability of the nozzle to fire adrop of ink. Clogging can be caused by evaporation of an organic solventor water from the interface of the liquid at the surface and/or withinthe nozzle. The inception of clogging may cause distortion of theprinted image or alphanumeric character. Eventually the clogged nozzlecan fail to fire and no image will be generated. Consequently, a printerservice routine, such as a printhead purge operation, may be required ona regular basis to avoid printing defects. However, it may be desirableto service the printhead as infrequently as possible, as servicing theprinthead can be wasteful of ink and requires that the printer beunavailable for normal printing operations.

A typical requirement for an inkjet ink is the ability to remain in thefluid condition in a printhead nozzle opening on exposure to air, whichis the so-called “decap” condition. This ability can allow a nozzle tofunction normally after a period of non-use. Examples of such periods ofnon-use may be during times of printer storage, maintenance, and/orduring normal operation of infrequently utilized printhead nozzles.Decap is sometimes referred to in the art as “latency” and these twoterms have been used interchangeably. The longer the decap time ratingof the ink, the longer the down times that can be handled oraccommodated by the printer. For example, a long decap time reduces theneed for servicing the printhead.

A longer decap time can be achieved, for example, by the use of certainless volatile solvents (a solvent with a lower vapor pressure) in theink formulation. However, such solvents do not dry quickly enough forhigh throughput printing operations and thus smearing of the print mayresult. Therefore, there is a need for inkjet inks that permit longerdecap time without sacrificing other beneficial properties, such as fastdrying time.

SUMMARY

The present disclosure includes systems and techniques relating tosolvent-based inkjet ink formulations. The subject matter described inthis specification can be embodied in an inkjet ink that includes anorganic solvent, a resin, a surfactant, and a colorant.

In one aspect of the disclosure, an inkjet ink includes an organicsolvent, a resin, a surfactant, and a colorant. The decap time of theink can be at least about 1 minute.

In some implementations, the organic solvent includes a fast solvent, anintermediate solvent, a slow solvent or their mixtures. The fast solventcan be selected from the group consisting of methanol, ethanol,propanol, iso-propanol, acetone, methyl ethyl ketone, methyl isobutylketone, pentane, hexane, heptane, methyl acetate, ethyl acetate, propylacetate, derivatives of the included solvents, and their mixtures. Insome examples, the intermediate solvent can be selected from the groupconsisting of C₄₋₈ alcohols, 1-methoxy-2-propanol, 2-methoxy ethanol,2-ethoxy ethanol, 1-methoxy-2-acetoxy propane, derivatives of theincluded solvents, and their mixtures. The slow solvent can be selectedfrom the group consisting of tripropylene glycol monomethyl ether,tripropylene glycol-n-butyl ether, propylene glycol phenyl ether,derivatives of the included solvents, and their mixtures.

In another aspect, the disclosure describes an inkjet ink including afast organic solvent (e.g., ethanol), a resin, a surfactant (such as afluorosurfactant), and a colorant. The decap time of the ink can be atleast about one hour.

In some implementations, the inkjet ink is substantially free of anintermediate organic solvent, a slow organic solvent, or combinationsthereof.

In some implementations, the inkjet ink has a drying time of less thanabout 2 seconds.

In some implementations, the fast solvent is selected from the groupconsisting of methanol, ethanol, propanol, iso-propanol, acetone, methylethyl ketone, methyl isobutyl ketone, pentane, hexane, heptane, methylacetate, ethyl acetate, propyl acetate, derivatives of the includedsolvents, and their mixtures.

In another aspect, the disclosure describes an inkjet ink including anintermediate organic solvent (e.g., a glycol ether having at least aboutfour carbon atoms), a resin, a surfactant (such as a fluorosurfactant),and a colorant. The decap time of the ink can be at least about onehour.

In some implementations, the inkjet ink is substantially free of a fastorganic solvent, a slow organic solvent, or combinations thereof.

In some implementations, the intermediate solvent is selected from thegroup consisting of C₄₋₈ alcohols, 1-methoxy-2-propanol, 2-methoxyethanol, 2-ethoxy ethanol, 1-methoxy-2-acetoxy propane, ethyl lactate,derivatives of the included solvents, and their mixtures.

In another aspect, the disclosure describes an inkjet ink including aslow organic solvent, a resin, a surfactant (such as afluorosurfactant), and a colorant. The decap time of the ink can be atleast about one day.

In some implementations, the inkjet ink is substantially free of a fastorganic solvent, an intermediate organic solvent, or combinationsthereof.

In some implementations, the slow organic solvent includes a glycolether (optionally having at least about 10 carbon atoms) or a dihydricalcohol (optionally having at least about 2 carbon atoms). The slowsolvent can be selected from the group consisting of tripropylene glycolmonomethyl ether, tripropylene glycol-n-butyl ether, propylene glycolphenyl ether, derivatives of the included solvents, and their mixtures.

In another aspect, the disclosure describes an inkjet ink including anorganic solvent (such as a slow solvent), a fluorosurfactant andoptionally a resin.

Implementations of the disclosure may include one or more of thefollowing features. In some implementations, the ink can be used in adrop on demand inkjet printer (such as, thermal inkjet printer). Theresin may be selected from the group consisting of rosin modifiedphenolic resin, phenolic resin, styrene-acrylic resin, polyketone resin,derivatives of the included resins, and their mixtures. In someimplementations, the surfactant includes a non-ionic surfactant or anionic surfactant. In some examples, the surfactant includes afluorosurfactant, a siloxane-based surfactant, an acetylenic diol-basedsurfactant, a hydrocarbon-based surfactant, and/or their mixtures.

In some implementations, the fluorosurfactant is selected from the groupconsisting of polyethylene oxide-b-poly(tetrafluoroethylene)polymers,2-(perfluoroalkyl)ethyl stearate, anionic lithium carboxylatefluorosurfactant, anionic phosphate fluorosurfactant, anionic phosphatesurfactant, amphoteric quaternary ammonium-acetate fluorosurfactant,derivatives of the included fluorosurfactants, and their mixtures. Thesiloxane-based surfactant, in some examples, can be selected from thegroup consisting of polysiloxane-b-ethylene oxide,polysiloxane-b-propylene oxide, polysiloxane-b-propylene oxide/ethyleneoxide, derivatives of the included siloxane-based surfactants, and theirmixtures.

In some implementations, the acetylenic diol-based surfactant isselected from the group consisting of2,4,7,9-tetramethyl-5-decyne-4,7-diol (TMDD),2,5,8,11-tetramethyl-6-dodecyne-5,8-diol, derivatives of the includedacetylenic diol-based surfactants, and their mixtures.

In some implementations, the hydrocarbon-based surfactant is selectedfrom the group consisting of polyoxyethylene (10) isooctylcyclohexylether, (1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol,polyethylene glycol tert-octylphenyl ether, polyoxyethylenesorbitanmonopalmitate, derivatives of the included hydrocarbon-basedsurfactants, and their mixtures. The surfactant can be present in anamount of less than about 5% by weight of the ink, from about 0% toabout 1% by weight of the ink, or from about 1% to about 5% by weight ofthe ink.

In some implementations, the inkjet inks may have one or more of thefollowing attributes. The ink can have a drying time of from about 0.5second to about 10 seconds, a viscosity of from about 1 centipoise toabout 25 centipoise, and a surface tension of from about 20 dynes/cm toabout 50 dynes/cm.

In some implementations, the organic solvent has a relative evaporationrate of at least about 1.0, from about 0.01 to about 0.99, or less thanabout 0.01. The decap time of an ink can be at least about 10 hours. Insome examples, the decap time of an ink with surfactant is from about 3to about 10 fold greater than an ink without surfactant. In someexamples, the decap time of the ink is at least about 15 minutes.

Yet another aspect of the disclosure provides an inkjet ink including anorganic solvent selected from the group consisting of a glycol ether, aglycol ether acetate, an alcohol, and their mixtures. The inkjet inkincludes a resin, a fluorosurfactant, and a colorant.

In another aspect, the disclosure describes a method of forming a markon a substrate (such as a porous substrate or a non-porous substrate).The method includes transferring an ink to the substrate to provide amark on the substrate.

In another aspect, the disclosure describes an inkjet printer includinga printhead, a cartridge, and a reservoir including an ink. In someimplementations, the nozzle diameter of the printhead or the cartridgeis from about 20 microns to about 100 microns.

In another aspect, the disclosure describes an inkjet ink including afast organic solvent, a resin and a colorant. The ink is substantiallyfree of an intermediate organic solvent, a slow organic solvent, orcombinations thereof; and the ink has a drying time of less than about 2seconds.

In some implementations, the ink includes a fluorosurfactant.

“Decap time” as used herein, refers to the period of time an inkjetnozzle can be left uncapped and idle before the inkjet nozzle starts tofire an ink drop improperly. Improper firing includes no drop is fired,firing with either misdirection, loss of color, or unacceptable decreaseof velocity.

“Relative evaporation rate” as used herein, refers to the evaporationrate value, as determined by the ASTM method D3359, relative to n-butylacetate.

It is to be further appreciated that certain features of the disclosure,which are, for clarity, described in the context of separateimplementations, can also be provided in combination in a singleimplementation. Conversely, various features which are, for brevity,described in the context of a single implementation, can also beprovided separately or in any suitable sub-combination.

The details of one or more implementations of the disclosure are setforth in the description below. Other features, objects, and advantagesof the invention will be apparent from the description and from theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-5 are a series of digital photographs of the first threeindividual alpha numeric codes, taken at decap times of 1 minute (FIG.1), 3 minutes (FIG. 2), 10 minutes (FIG. 3), 15 minutes (FIG. 4), andovernight (FIG. 5), with the fast solvent F-2 in a thermal inkjetcartridge.

DETAILED DESCRIPTION

The present disclosure relates to solvent-based ink formulations. Suchink formulations can be advantageously used for improving decap time ofa printhead in an inkjet printer. The decap times can be assessed by thenumber of marks a printhead needs to make to obtain both a legible mark(such as, of an alphanumeric code) and a perfect mark; both beingdetermined at arm's length. The quality of the mark can be determined incomparison to a control image generated immediately after the ink isloaded into the printhead or the cartridge. The lesser the number ofmarks a printhead needs to make to obtain a legible and perfect mark,the better would be the quality of the ink. In some implementations ofthis disclosure, the number of marks a printhead needs to make to obtainboth a legible mark and a perfect mark is less then about 10, e.g., lessthen about 9, less then about 8, less then about 7, less then about 6,less then about 5, less then about 4, less then about 3, or less thenabout 2. The longer decap times can be achieved, for example, by use ofsurfactants in inks without sacrificing other beneficial properties suchas fast drying times. The solvent in an ink can be selected based on thedesired dry time required for a substrate, and the ink formulation canbe tailored to extend its decap time without compromising the desireddry time. The solvent-based ink formulations of the disclosure canprovide a decap time from about a few seconds to about at least a fewdays. In some implementations, the decap time is about 1 minute, e.g.,about 2 minutes, about 5 minutes, about 10 minutes, about 20 minutes,about 30 minutes, about 40 minutes, about 50 minutes, or about 60minutes. In some implementations, the decap time is about 1 hour, e.g.,about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 6hours, about 7 hours, about 8 hours, about 9 hours, about 10 hours,about 11 hours, about 12 hours, about 15 hours, about 18 hours, or about21 hours. In some implementations, the decap time is about 1 day, e.g.,about 2 days, about 3 days, about 4 days, about 5 days, about 6 days,about 7 days, about 8 days, about 9 days, or about 10 days.

In the case of inkjet printers with the inks described in thisdisclosure, minimal intervention and/or maintenance may be required overlong idle times (i.e., decap times). For highly volatile andintermediate volatility solvents, all nozzles can recover after 1-2images (such as an alpha numeric code) are printed after a certain decaptime (this can be true for up to about 24 hours idle time); for lowvolatility solvents, the idle time may reach as long as 4 days afterwhich all nozzles can be recovered without any ink purge cycles. Therapid recovery of nozzles leads to good quality images (such as, alegible image at arm's length or a perfect image). The length of timeuntil which the ink can consistently continue to produce a legible and aperfect image in four or less attempts can be considered to be the decaptime of that ink.

Ink formulations can include solvent, resin, colorant, and surfactant.Inks described herein typically have chemical and physical propertiesthat allow the inks to be jetted onto a substrate by an inkjet printer(e.g., by one or more nozzles of a printhead of an inkjet printer).

Drying time is an important attribute for solvent-based inkformulations, especially inks using fast solvents. Though their decaptime in the printhead is extended, the time required for ink printedonto a non-porous substrate to become dry to touch, remains reasonable.Dry time is measured by printing an image onto a non-porous substrate,e.g., oriented polypropylene, and allowing the printed image to becontacted by a stationary metal post at a prescribed time followingprinting. Any smearing of the image indicates a failure due to non-dryink. In some implementations of this disclosure, the drying time is fromabout 0.5 second to about 10 seconds, e.g., from about 1 second to about9 seconds, from about 2 seconds to about 8 seconds, from about 3 secondsto about 7 seconds, or from about 4 seconds to about 6 seconds. In someother implementations, the drying time is about 0.5 second, e.g., about1 second, about 2 seconds, about 3 seconds, about 4 seconds, about 5seconds, about 6 seconds, about 7 seconds, about 8 seconds, about 9seconds, or about 10 seconds.

In some implementations, the viscosity of the inks is about 5centipoise, e.g., about 10 centipoise, about 11 centipoise, about 12centipoise, about 13 centipoise, about 14 centipoise, about 15centipoise, about 20 centipoise, or about 25 centipoise. In someimplementations, the viscosity of the inks is about 1 centipoise, e.g.,about 2 centipoise, about 3 centipoise, or about 4 centipoise. In someimplementations, the viscosity of the inks is about 10 centipoise, e.g.,about 11 centipoise, about 12 centipoise, about 13 centipoise, or about14 centipoise.

In some implementations, the ink has a surface tension of from about 20dynes/cm to about 50 dynes/cm, e.g., from about 20 dynes/cm to about 30dynes/cm, from about 30 dynes/cm to about 40 dynes/cm, or from about 40dynes/cm to about 50 dynes/cm.

Solvent

Generally, the solvent can be any material that can dissolve the resinand other materials in the inkjet inks. Depending on the choice of asubstrate for which an inkjet ink is targeted, a solvent (such as anorganic solvent) can be selected based on the evaporation rate of asolvent. Certain non-aqueous inks have been disclosed in U.S. PatentApplication Publications US 2005/0039634 (Hermansky), US 2009/0246377(Robertson et al.), and US 2010/0098860 (Robertson et al.) and inpublished PCT applications WO 2010/042104 (Barreto et al.) and WO2010/042105 (Barreto), the entire disclosures of which is incorporatedherein by reference.

The evaporation rate of a solvent can typically be determined by theASTM method D3359, and can be reported as a relative evaporation rate(RER), usually relative to n-butyl acetate. Based on this RER, thesolvents can be grouped in a manner depending on the applicationenvisioned. The solvents are categorized as a fast, intermediate and aslow solvent according to their RERs: solvents having a RER greater than1.0 can be grouped as fast solvents; solvents having a RER from about1.0 to about 0.01 can be grouped as intermediate solvents; and solventshaving a RER less than about 0.01 can be grouped as slow solvents. TheRERs can typically be correlated with the volatility of a solvent. Afast solvent typically evaporates faster and can lead to rapidlyincreasing viscosity of an ink. Although a solvent may be mentioned as asingle chemical entity, derivatives of such solvents can include itsstructural isomers and other oligomers. The organic solvents describedherein may either be used in an anhydrous or wet form.

Examples of fast solvents can include methanol, ethanol, propanol,iso-propanol, acetone, methyl ethyl ketone, methyl isobutyl ketone,pentane, hexane, heptane, methyl acetate, ethyl acetate, propyl acetate,tert-butyl acetate, tert-butanol, tetrahydrofuran, and their mixtures.

In some implementations, the weight % of fast solvent in inks can beabout 5%, e.g., about 10%, about 15%, about 20%, about 25%, about 30%,about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about65%, about 70%, about 75%, about 80%, about 85%, about 90%, or about95%. In other implementations, the weight % of fast solvent in inks canbe greater than about 75%, e.g., greater than about 80%, greater thanabout 85%, greater than about 90%, or greater than about 95%.

Examples of intermediate solvents can include C₄₋₈ alcohols (e.g.,butanol, pentanol, hexanol, heptanol, octanol, and the like), propyleneglycol ethers (e.g., propylene glycol mono methyl ether, propyleneglycol mono ethyl ether, propylene glycol n-propyl ether, propyleneglycol n-butyl ether, and the like), dihydric alcohols (e.g., ethyleneglycol, propylene glycol, butylene glycol, and the like),1-methoxy-2-acetoxy propane, cyclohexanone, and their mixtures.

In some implementations, the weight % of intermediate solvent in inkscan be about 5%, e.g., about 10%, about 15%, about 20%, about 25%, about30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%,about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, orabout 95%. In other implementations, the weight % of intermediatesolvent in inks can be from about 60% to about 90%, e.g., from about 60%to about 80%, from about 70% to about 90%, or from about 70% to about80%.

Examples of slow solvents can include, but are not limited to, glycolethers having at least about 10 carbon atoms (e.g., at least about 11carbon atoms, at least about 12 carbon atoms, at least about 13 carbonatoms, at least about 14 carbon atoms, or at least about 15 carbonatoms), dipropylene glycol methyl ether, dipropylene glycol methyl etheracetate, dipropylene glycol n-butyl ether, tripropylene glycolmonomethyl ether, tripropylene glycol-n-butyl ether, propylene glycolphenyl ether, and their mixtures. The RERs of certain glycol ethers havebeen reviewed by Smith, R. L., in Environmental Health Perspectives,Vol. 57, pp. 1-4 (1984), the entire disclosure of which is incorporatedherein by reference. Examples of commercial solvents include “DowanolTPM tripropylene glycol methyl ether,” and “Dowanol PM propylene glycolmethyl ether” available from Dow Chemical (Midland. Mich.).

In some implementations, the weight % of slow solvent in inks can beabout 5%, e.g., about 10%, about 15%, about 20%, about 25%, about 30%,about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about65%, about 70%, about 75%, about 80%, about 85%, about 90%, or about95%. In other implementations, the weight % of slow solvent in inks canbe from about 5% to about 60%, e.g., from about 5% to about 50%, fromabout 5% to about 40%, from about 5% to about 30%, from about 5% toabout 20%, from about 20% to about 30%, from about 20% to about 40%, orfrom about 20% to about 50%.

In some implementations, the ink including a fast solvent issubstantially free of the intermediate, or slow solvents. Substantiallyfree refers to the weight % of a component being less than about 10%,e.g., less than about 9%, less than about 8%, less than about 7%, lessthan about 6%, less than about 5%, less than about 4%, less than about3%, less than about 2%, or less than about 1%.

The solvent can be non-toxic, environmentally friendly, e.g., isEPA-approved and does not produce hazardous pollutants, stable withrespect to the materials in the ink, and/or cost effective forrelatively large scale manufacturing. Other solvents can be used.

Resins

The resin typically provides the ink with a desired viscosity, thermalstability, flexibility, and adhesion properties. The inks can includeresins such as a rosin modified phenolic resin, a phenolic resin, astyrene-acrylic resin, a polyketone resin, derivatives of the includedresins, or their mixtures. The inks can include other types of resinssuch as polyvinyl butyral (PVB), acrylic, polyurethane, polyamide,polyvinylpyrrolidone (PVP), or vinyl resins.

Examples of resins include, but are not limited to, acacia (gum arabic);gum ghatti; guar gum; locust (carob) bean gum; karaya gum (sterculiagum); gum tragacanth; chicle; highly stabilized rosin ester; tall oil;manila copais; corn gluten; coumarone-indene resins; crown gum; damargum; p, alpha-dimethylstyrene; gum elemi; a rosin glycerol ester; anethylene vinyl acetate (EVA); a polyamide resin; ethylene oxide polymerand its adducts; ethylene oxide/propylene oxide copolymer and itsadducts; galbanum resin; gellan gum; ghatti gum; gluten gum; gualac gum;guarana gum; heptyl paraben; cellulose resins, including methyl andhydroxypropyl; hydroxypropyl methylcellulose resins;isobutylene-isoprene copolymer; mastic gum; oat gum; opopanax gum;polyacrylamide; modified polyacrylamide resin; polylimonene;polyisobutylene (min. MW 37,000); polymaleic acid; polyoxyethylenederivatives; polypropylene glycol (MW 1200-3000); polyvinyl acetate;polyvinyl alcohol; polyvinyl polypyrrolidone; polyvinyl pyrrolidone;rosin, adduct with fumaric acid, pentaerythritol ester; rosin, gum,glycerol ester; rosin, gum or wood, pentaerythritol ester; rosin, gum orwood, partially hydrogenated, glycerol ester; rosin, gum or wood,partially hydrogenated, pentaerythritol ester; rosin, methyl ester,partially hydrogenated; rosin, partially dimerized, glycerol ester;rosin, partially hydrogenated; rosin and rosin derivatives; rosin,polymerized, glycerol ester; rosin, tall oil, glycerol ester; rosin,wood; rosin, wood, glycerol ester; purified shellac; styrene; styreneterpolymers; styrene copolymers; sucrose acetate isobutyrate; terpeneresins, natural and synthetic; turpentine gum; vinylacetate; vinylchloride-vinylidene chloride copolymer; zanthan gum; and zein.

Examples of commercial resins include Joncryl family of resins(available from BASF), Reactol K3107 (a phenolic resin from Hexion),Resin SK (a polyketone resin from Evonik), Alnovol PN320 (a novolakphenolic resin from Cytec), Laropal A81 (an aliphatic aldehyde resinfrom BASF), and Foral 85 hydrogenated rosin ester resin, available fromHercules Chemical Company, Inc.; 111 South Street, Passaic, N.J. 07055.

Surfactant

The surfactant (surface active agent) compound can serve to alter thesurface tension of the ink composition, and can be anionic (such assulfate esters, carboxylates, sulfonates, or phosphonates), cationic,nonionic (such as polyol based, polyglycerols based, fluorocarbon based,siloxane-based, alkyl phenol based, or polyoxyethylene based) oramphoteric (such as phosphatides, imidazoline derivatives, or betaines)surfactant compound, such as those described in “Surfactants andInterfacial Phenomena,” Second Edition, M. J. Rosen, 1989, John Wileyand Sons, Inc., New York, pages 1-32, the entire disclosures of which isincorporated herein by reference.

While not intending to be bound by any particular theory, it is believedthat, consistent with the principles involving Langmuir-Blodgett (LB)films and water, but herein applied to liquid inks, surfactant moleculesin the inkjet ink formulations can organize rapidly at the ink/airinterface within the jetting nozzle. Typically, the ink surface withinthe opening of the jetting nozzle, being a confined surface undertension, can cause the surfactant molecules to organize in a densemanner. Details of the teachings of Langmuir and Blodgett may be foundat http://www.ksvinc.com/LB.htm (“Langmuir and Langmuir-Blodgett Films:WHAT and HOW?” KSV Instruments Oy (Helsinki, Finland)) or in the articleentitled “Langmuir Blodgett Films.” I. R. Peterson, Journal of Physics,D 23, 4, (1990) 379-95, the entire disclosure of which is incorporatedherein by reference.

The inclusion of a surfactant within an ink formulation can lead to abarrier in the form of a layer of surfactant at the interface of air andbulk ink, thereby reducing, and preferably substantially eliminating,the ability of the solvent to evaporate from the bulk ink. By reducingthe solvent evaporation rate, and preferably entirely preventing solventevaporation of the ink formulations, the decap time can be increased. Atthe same time, once an inkjet ink is jetted onto a substrate, fastevaporation (i.e., fast drying time) can occur because the surfactantmolecules can spread out over a larger surface area instead of beingconfined to a surface that is under tension.

Fluorosurfactants are surfactants that can either be ionic (with thefluorine-containing moiety being part of either the cationic or theanionic part) or nonionic (such as fluorocarbon chain-containingalcohols). The fluorosurfactants can be ethoxylated surfactants (i.e.,polyethyleneoxide modified) or polytetrafluoroalkylene surfactants.Ethoxylated surfactants include one or more of ethylene oxide monomericunits. Polytetrafluoroalkylene surfactants include one or more oftetrafluoroalkylene units. Examples of fluorosurfactants includepolyethylene oxide-b-poly(tetrafluoroethylene)polymers,2-(perfluoroalkyl)ethyl stearate, anionic lithium carboxylatefluorosurfactant, anionic phosphate fluorosurfactant, anionic phosphatesurfactant, amphoteric quaternary ammonium-acetate fluorosurfactant,fluoroaliphatic polymeric esters, their derivatives, and their mixtures.Examples of commercial fluorosurfactants include Zonyl family offluorosurfactants (e.g., Zonyl FSO 100, Zonyl FSN, Zonyl FTS) andCapstone family of fluorosurfactants (available from DuPont Chemicals,Wilmington, Del.), or Fluorad FC 170-C, FC171, FC430 and FC431 availablefrom 3M of St. Paul, Minn. Hermansky (see above) discloses the completedrying of the inks in the presence of Zonyl FSX surfactant.

Siloxane-based surfactants are surfactants which can be copolymers ofsilyl ethers and epoxy (ethylene oxide, propylene oxide) oligomers orpolymers. Examples of siloxane-based surfactants includepolysiloxane-b-ethylene oxide, polysiloxane-b-propylene oxide,polysiloxane-b-propylene oxide/ethylene oxide, their derivatives, andtheir mixtures. Examples of commercial siloxane-based surfactantsinclude copolymers such as SILWET® copolymers including Silwet L-7604,available from GE Silicones; Troysol Q-148 and 5366 available from TroyChemical.

Acetylenic diol-based surfactants are surfactants which can beacetylenic diols comprising hydrophobic groups at the end of theacetylenic spacer and hydrophilic and/or hydrophobic ethers hanging offof the hydroxyl groups. Examples of acetylenic diol-based surfactantsinclude, 2,4,7,9-tetramethyl-5-decyne-4,7-diol (TMDD),2,5,8,11-tetramethyl-6-dodecyne-5,8-diol, their derivatives, and theirmixtures. Examples of commercial acetylenic diol-based surfactantsinclude Dynol series (Dynol 604) and Surfynol series (Surfynol 104, 420,465, 485, TG-E, SE, etc.) available from Air Products.

Hydrocarbon-based surfactants are surfactants which can bepolyoxyethylenated alkyl phenols (APE type), polyoxyethylenated shortchain alcohols (AE type), or long chain organic acid esters. Examples ofhydrocarbon-based surfactants include polyoxyethylene (10)isooctylcyclohexyl ether, (1,1,3,3-tetramethylbutyl)phenyl-polyethyleneglycol, polyethylene glycol tert-octylphenyl ether,polyoxyethylenesorbitan monopalmitate, their derivatives, and theirmixtures. Examples of commercial hydrocarbon-based surfactants includeTriton X Series and Tergitol Series both from Dow Chemical; the TWEENSeries from ICI Americas; and the Igepal Series from Hallstar.

The surfactants can be present in varying amounts in the inkjet ink,depending on the other ingredients. The surfactants, as a weight % ofthe ink, can be present from about 0% to about 5%, e.g., from about 0%to about 1%, from about 1% to about 2%, from about 2% to about 3%, fromabout 3% to about 4%, or from about 4% to about 5%. In someimplementations, the surfactants, as a weight % of the ink, can bepresent from about 1.1% to about 5%, e.g., from about 1.1% to about 2%,from about 1.1% to about 3%, or from about 1.1% to about 4%. In someimplementations, the surfactants, as a weight % of the ink, can bepresent less than about 5%, e.g., less than about 4%, less than about3%, less than about 2%, less than about 1%, or less than about 0.5%. Thedecap time of an ink with a surfactant can increase from about 3 toabout 10 fold compared to an ink without a surfactant. In someimplementations, the decap time of an ink with a surfactant can increaseabout 3 fold, e.g., about 4 fold, about 5 fold, about 6 fold, about 7fold, about 8 fold, about 9 fold, or even about 10 fold compared to anink without a surfactant.

The addition of surfactants can provide an extended decap time withoutcompromising the drying time on a substrate. Surfactants can alter theviscosity of the ink formulations to some extent and can further preventthe viscosity of the inks in the reservoir to alter minimally. Forexample, the viscosity of the inks can be from about 1 centipoise toabout 25 centipoise, e.g., from about 5 centipoise to about 20centipoise, or from about 10 centipoise to about 15 centipoise. Thesurfactants can alter the surface tension of the inks at the air-inkinterface during idle time and can aid in decreasing the solventevaporation rate.

Colorant

The ink may include a colorant, which provides color to the ink. The inkcan contain a sufficient amount of a colorant that the ink has color,but not so much as to interfere with other desirable qualities, such assurface tension or viscosity.

An ink can include one or more colorants (e.g., one or more pigments,one or more dyes, or their mixtures). Colorants can provide an ink with,for example, a desired color and/or opacity. Exemplary colors caninclude black, cyan, magenta, yellow, red, blue, green, brown, or theircombinations.

Examples of suitable pigments include Color Index Pigment Black 7;Pigment Blue 15; Pigment Red 112, 146, 170 and 208; Pigment Yellow 17and 83; Pigment Green 7; carbon black, graphite; and pigment whitetitanium dioxide. Additional examples are disclosed in, e.g., U.S. Pat.No. 5,389,133, the entire disclosures of which is incorporated herein byreference. The pigment may also have a modifying group on its surface,such as an oxygen-containing functionality (e.g., a carboxyl or phenolgroup). An example of a commercially available pigmented colorant can be“Special Black 4A” available from Evonik Degussa (Germany).

Examples of dyes include Orasol Pink 5BLG, Black RLI, Blue 2GLN, Red G,Yellow 2GLN, Blue GN, Blue BLN, Black CN, and Brown CR (all availablefrom Ciba-Geigy, Inc., Mississauga, Ontario); Morfast Blue 100, Red 101,Red 104, Yellow 102, Black 101, and Black 108 (all available from MortonChemical Company, Ajax, Ontario); and a mixture thereof.

Other Modifying Agents in the Formulations

The inkjet inks can contain smaller amounts of other ingredients withouthindering the desired properties of the inks Such ingredients caninclude dispersants, anti-foaming agents, wetting agents, viscositymodifiers, and light stabilizers.

Ink Preparation

A pigment concentrate can be prepared by combining a pigment with anamount of at least some (e.g., all) components of an ink to be preparedto provide a concentrate having a higher concentration of pigment thanthe final ink. The pigment concentrate can improve pigment grinding andreduce process time.

While not intending to be bound by any particular theory, it is believedthat in the pigment concentrate, the number density of pigment particlesis increased, which allows for more particle-particle andparticle-grinding media collisions, which in turn decreases the periodof time needed to reach a desired particle size. Additionally, in theconcentrate, the particles have higher odds of coming in contact withdispersant/surfactant molecules, if present. These materials can adsorbonto the surface of the particles so that the particles with reducedsize do not agglomerate. By increasing the odds of particle-dispersantcollisions, the grind time can be reduced and the particle sizestability can be increased.

For example, to prepare a carbon black pigment concentrate, the amountof dispersant to be used can be calculated based on the desired pigmentparticle size, the calculated pigment surface area (supplied by thepigment manufacturer), or both. A fluid vehicle and dispersant can becharged into an appropriate vessel. The vehicle and dispersant can bemixed until fully blended (some gentle heating may be necessary if thedispersant is a solid). The vehicle/dispersant mixture can be moved to ahigh shear mixer and the pigment can be slowly charged. The materialscan be milled to obtain a pigment concentrate.

For a liquid ink, all liquid ingredients can be mixed and, if necessary,the ink can be filtered through a desired filter.

Printers

A drop-on-demand inkjet printer can be defined as a piezo driven systemor a thermally driven system. In the case of the piezo system, a printerconsists of electronics and software necessary to control an inkreservoir and a piezo driven inkjet assembly (an array of inkjet nozzlesarranged in a regular pattern), where a reservoir is either directly orindirectly attached to a printing assembly. Direct attachment results inan integral printhead whereas indirect attachment results in a jettingassembly located some distance away from the reservoir with the twocomponents connected by an ink umbilical that delivers ink to the inkjetjetting assembly. In the case of thermal inkjet system, a printerconsists of electronics and software necessary to drive a fullyintegrated reservoir and jetting assembly in a stand-alone holder organged together to increase image swath or resolution. However, thereare instances where a “bulk” ink reservoir can be used to feed ink to athermal inkjet assembly through an umbilical. The electronics andsoftware controls in both cases dictate when a drop is to be ejectedfrom the inkjet assembly based on the desired image to be printed.

Drop on demand printers are described in more detail, e.g., in U.S. Pat.No. 5,265,315; Thermal inkjet printheads are described, e.g., in U.S.Pat. Nos. 4,727,384 and 4,500,895; and, piezoelectric inkjet printheadsare described in, e.g., U.S. Pat. Nos. 4,825,227, 4,937,598, 5,659,346,5,757,391, and 7,052,117. The entire disclosures of these patents areincorporated herein by reference.

Manufacturers of piezo inkjet assemblies include Dimatix, Xaar, andXerox. Manufacturers of thermally driven inkjet assemblies integrated toa reservoir (commonly referred to as a thermal inkjet cartridge) includeHewlett Packard, Lexmark, and Olivetti.

The inks described can be utilized in either a piezo driven or athermally driven inkjet assembly by adjusting the viscosity of an ink.In general, piezo driven inkjet assemblies can utilize inks with aviscosity between 7 cPs and 25 cPs depending on the nozzle geometry,whereas thermally driven inkjet assemblies can utilize inks with aviscosity between 1 cPs and 5 cPs depending on the nozzle geometry.

Inkjet assemblies, both piezo and thermally driven systems, can bemanufactured (such as by laser drilling, chemical etching) withdifferent nozzle diameters depending on the desired drop volume. Ingeneral, smaller diameter nozzles can result in ejection of lower dropvolumes and larger diameter nozzles can result in ejection of higherdrop volumes. In the case of thermal inkjet assemblies, multiple nozzlediameters can be integrated into a single jetting assembly such thatmultiple drop volumes can be ejected from a single cartridge. In someimplementations, nozzle diameter can be from about 20 microns to about100 microns, e.g., from about 30 microns to about 100 microns, fromabout 40 microns to about 100 microns, from about 50 microns to about100 microns, from about 60 microns to about 100 microns, from about 70microns to about 100 microns, from about 80 microns to about 100microns, or from about 90 microns to about 100 microns.

Printing Process

Inks can be jetted by either thermal inkjet cartridges or piezo drop ondemand printheads. Examples of thermal inkjet cartridges are thosecommercially available from Hewlett Packard (such as HP45); Lexmark(such as Model 34); and Olivetti (such as IN501). Examples of piezo dropon demand printheads can include commercially available models fromDimatix (such as Q or S Class) and Xaar (such as a XJ500). Examples ofthermal inkjet printers that would allow solvent-based inks to be jettedare: DeskJet model 710 from Hewlett Packard, the model Z845 fromLexmark, and the model Simple Way from Olivetti. Examples of piezo-basedprinters that would allow solvent-based inks to be jetted are:Markem-Imaje models 5200 and 4040. To print inks, an ink is loaded intoa reservoir where it is either pumped or fed by gravity to a jettingchamber of a cartridge or printhead. In the case of the thermal inkjetcartridge, a liquid ink is ejected from a printhead by being rapidlyheated, causing a rapid phase change from liquid to gas, thus causing arapid volume expansion and subsequently causing a droplet to eject froman orifice. In the case of a piezo-based device a liquid ink is ejectedfrom a printhead by activation of a piezo transformer (PZT), whichcauses a pressure wave to be exerted upon the ink and an ink droplet canbe ejected from an orifice. Both devices are referred to asdrop-on-demand since a droplet of ink is ejected only when a heater orPZT material is activated. Each cartridge or printhead contains an arrayof several orifices across its width. Activation of each orifice in suchan array is performed methodically by the printer such that an image isformed drop-wise on a substrate, which is positioned a short distancefrom the orifice array. The printers are designed such that an orificearray and a substrate move relative to one another in order to form animage. In continuous ink jet printing, a continuous stream of conductiveink droplets is ejected from a nozzle. The droplets areelectrostatically deflected to address several vertical pixels as thesubstrate moves relative to the nozzle. Ink droplets that are notintended or needed to form a desired image on the substrate are fullydeflected into a gutter and recycled to the ink supply. CIJ inks containan additive (such as, a conductive aid) that imparts conductivity andallows the droplets to be deflected. The process of jetting ink dropletscontinuously and directing unneeded drops to the gutter allows the CIJsystems to utilize fast evaporating solvents without concern for decapand nozzle clogging, as the nozzle is effectively never idle duringoperation.

In the case of inks that utilize fast evaporating solvents, uponcontacting a substrate, which is typically non-porous and at roomtemperature, a solvent in the liquid ink evaporates and a film forms onthe substrate. In the case of inks that utilize intermediate evaporatingsolvents, upon contacting a substrate, which is typically semi-porousand at room temperature, a liquid ink dries by a combination ofevaporation and absorption. In the case of inks that utilize slowevaporating solvents, upon contacting a substrate, which is typicallyporous and at room temperature, a liquid ink flows rapidly into the voidspaces in the substrate and dries primarily by absorption. In all threecases of solvents, it is possible in some settings to assist drying ofthe inks by adding an in-line drying capability. In some implementationsof printing using the described inks, the drying of the inks on thesubstrate is unassisted (such as without the use of external dryingmechanisms e.g., fans).

Substrates

The inks can be applied to either porous or non-porous substrates suchas flexible packaging films (for example, polypropylene, polyethylene,polyethylene terephthalate, polystyrene, or poly(lactic acid) films),rigid plastic materials (for example polypropylene, polyethylene,polyethylene terephthalate, polystyrene, poly(lactic acid),polyvinylchloride materials), corrugated cardboard (for example,bleached, unbleached, and coated cardboard), boxboard (for example,glossy coated, matte coated, and uncoated boxboards), bottle materials(for example, glass, polyethylene terephthalate, polyethylene,polypropylene, and poly(lactic acid) materials).

Additionally, as indicated in each of Examples 1 through 12, thesolvent-based ink formulations can be tailored for a certain operatingtemperature, for a certain viscosity, and for a certain nozzle diameter,which defines the surface under tension.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art of solvent-based inkjet inks. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing, suitable methods and materials are described below.In case of conflict, the present specification, including definitions,will control. In addition, the materials, methods, and examples areillustrative only and not intended to be limiting.

EXAMPLES Example 1 Procedure for Making Inks and Pigmented Concentrate

Procedure for Making Inks

Step 1:

A resin and solvent are measured into a glass beaker and the solution isstirred (with either a magnetic stirrer or a propeller blade at about200-400 rpm) at room temperature until homogeneous. This will typicallyrequire between 10 and 200 minutes. The surfactant is measured into aseparate vessel and slowly added to the homogenous, stirring resin andsolvent solution. The mixing was continued until homogeneous, but notfor less than about 10 minutes. The colorant is measured into a separatevessel. If colorant is a dye, no prior processing is necessary. Ifcolorant is a pigmented dispersion, see Step 1A for the preparation ofpigmented concentrate. The colorant is added slowly to the homogenous,stirring solution and continued to mix until colorant has been fullyincorporated into solution, but not for less than about 20 minutes. Theviscosity of ink was measured using Brookfield DV series viscometer. Theink was loaded into a syringe and filtered through a 1.0 micron syringefilter (e.g., Whatman Puradisc® 25GD; with GMF-150 media; p/n 6783-2510)placed on the exit of the syringe. The filtered ink can now be loadedinto printer reservoir.

Step 1A:

Procedure for Making Pigmented Concentrate:

The solvent was measured into a stainless steel vessel and stirred usinga high speed Cowles® type blade at about 1000 rpm. The dispersant wasmeasured into a separate vessel and slowly added to the mixing solventuntil homogeneous, but not for less than about 15 minutes. The pigmentwas measured into a separate vessel and slowly added to the mixingsolvent until all of the pigment has been wetted by the solution. Themixer speed was increased to about 2000-5000 rpm and mixed for about 30minutes until the solution was homogeneous and all of the pigment waswetted. The mixer was stopped and the stainless steel vessel moved toBasket-style media mill, Hockmeyer Micro; 1/16 gallon model. The mediamill was charged with appropriate media such as YTZ 0.4-0.6 mm ceramicmaterial and processed at about 3000-4000 rpm for not less than 2 hoursor until solution passes easily through a 1 micron filter (e.g., WhatmanPuradisc® 25GD; with GMF-150 media; p/n 6783-2510). This pigmentedconcentrate was used in Step 1 above. Two pigmented concentrates wereprepared. Pigmented Concentrate-1 containing 61.2% glycol ether TPM,10.2% Solsperse 32000, and 28.6% Special Black 4A Pigment. PigmentedConcentrate-2 containing 72.4% glycol ether TPM, 7.3% Solsperse 32000,and 20.3% Special Black 4A Pigment.

Example 2 Inks with Fast Solvents

The inks of the formulation F-1 to F-8 (Table 1) were prepared accordingto the method described in Example 1. Each column indicates the weight %of the ingredient in the final formulation. The viscosity of the inks inTable 1 were measured using Brookfield DV Series Viscometer with a ULAAdapter at 72° F. using spindle 00 operating at 60 rpm spindle speed.The dry time was performed as described. Ink was loaded into apreviously unfilled thermal inkjet cartridge, the printhead was purgedand confirmed that all nozzles were operable. An image was printed on anon-porous substrate and good image quality was immediately confirmed.The web speed was set at prescribed rate and the fixed post moved intoposition. An image was printed on a substrate and images allowed to passby the fixed post. The images were inspected for signs of smear thatwould indicate wet ink. The test was performed at 150 dpi in processdirection and 600 dpi in the cross process direction and dry time wasrecorded.

TABLE 1 Inks with fast solvents Ingredient F-1 F-2 F-3 F-4 F-5 F-6 F-7F-8 Ethanol 93.4 91.4 91.4 91.3 90.0 91.4 92.4 90.4 (anhydrous) ReactolK3107 2.9 2.9 2.9 — — 2.9 2.9 2.9 Alnovol PN430 — — — 3.0 — — — —Joncryl 682 — — — — 4.5 — — — Orasol Black 3.7 3.7 3.7 3.7 3.5 3.7 3.73.7 RLI Zonyl FSO100 0.0 2.0 — 2.0 2.0 — — — Zonyl FSN — — 2.0 — — — — —Silwet L7604 — — — — — — 1.0 — Triton X-100 — — — — — — — 3.0 Dynol 604— — — — — 2.0 — — Viscosity 1.52 1.55 1.94 1.70 1.65 1.71 1.72 1.79 (cPsat 72° F. Dry time 0.5 1.5 1.25 >2 1.0 0.5 0.5 1.5 @ 150 dpi (s)

Example 3 Decap Testing for Fast-Solvents

Ink was loaded into a previously unfilled thermal inkjet cartridge, theprinthead was purged and a control image consisting of 24 individualalpha numeric codes (in FIGS. 1-5, “ENJOY BY 20 JUN 08” represents analpha numeric code) was immediately generated. The printer was allowedto sit idle for one minute and then an image consisting of 24 individualalpha numeric codes was generated. The number of codes that had to begenerated to obtain both a legible code at arm's length (L*) and aperfect code (P*) was recorded. The printer was allowed to sit idle for3 minutes and then an image consisting of 24 individual alpha numericcodes was generated. This line of testing was continued for 5, 10, 15,60 minutes and overnight. The results are presented in Table 2. For theink F-1, after 1 min. of decap time, the eighteenth code was legiblewhereas none of the codes were perfect. For the ink F-4, after 1 min. ofdecap time, the second code was both legible and perfect.

FIGS. 1-5 are each the first three individual alpha numeric codesgenerated with the ink F-2 after 1 min. (FIG. 1), 3 min. (FIG. 2), 10min. (FIG. 3), 15 min. (FIG. 4), and overnight (FIG. 5) decap times. Thealpha numeric code on the right in each Figure is the first imagegenerated. In FIG. 1, the first legible image was the second image whilethe first perfect image was the third image. In Table 2, the ink F-2continues to produce a legible and a perfect image for a decap time ofat least about overnight (16 hours) while the ink F-6 was determined toproduce a legible and a perfect image for a decap time of about 1 min.

TABLE 2 Decap Test Results Time F-1 F-2 F-3 F-4 F-5 F-6 F-7 F-8 (min.)L* P* L* P* L* P* L* P* L* P* L* P* L* P* L* P* 1 18 >24 2 3 1 3 2 2 5 81 1 >24 >24 12 14 3 >24 >24 3 4 2 3 2 2 n/a n/a 2 20 18 >24 9 115 >24 >24 1 4 1 3 1 2 n/a n/a 11 14 19 >24 11 12 10 >24 >24 1 2 2 2 1 25 8 10 15 20 24 14 20 15 >24 >24 1 1 2 2 1 2 2 3 12 10 17 19 11 1460 >24 >24 1 1 1 1 2 2 1 1 7 10 18 20 9 10 overnight >24 >24 1 1 2 2 1 11 1 >24 >24 >24 >24 20 22

Example 4 Inks with Fast Solvents

The inks of the formulation F-9 to F-14 (Table 3) can be preparedaccording to the method described in Example 1. Each column indicatesthe weight % of the ingredient in the final formulation.

TABLE 3 Inks with fast solvents Ingredient F-9 F-10 F-11 F-12 F-13 F-14Ethanol 88-96 88-96 88-96 88-96 88-96 88-96 Reactol K3107 2-4 — — 2-4 —— Alnovol PN430 — 2-4 — — 2-4 — Joncryl 682 — — 2-4 — — 2-4 Orasol BlackRLI 3-5 3-5 3-5 3-5 3-5 3-5 Zonyl FSO100 0-3 0-3 0-3 — — — Zonyl FSN100— — — 0-3 0-3 0-3

Example 5 Inks with Intermediate Solvents

The inks of the formulation I-1, I-2, and I-6 (Table 4) were preparedaccording to the method described in Example 1. Each column indicatesthe weight % of the ingredient in the final formulation. The viscosityof the inks in Table 4 were measured using Brookfield DV SeriesViscometer with a ULA Adapter at 72° F. using spindle 00 operating at 30rpm spindle speed.

TABLE 4 Inks with intermediate solvents Ingredient I-1 I-2 I-6 PMsolvent 77.7 76.2 76.2 Reactol K-3107 19.7 19.3 19.3 Orasol Black RLI2.6 2.5 2.5 Zonyl FSO 100 0 2 0 Zonyl FSN 100 0 0 2 Viscocity, cPs at10.4 10.7 10.6 40° C.

Example 6 Decap Testing for Intermediate Solvents

Ink was loaded into a Dimatix Skywalker 128/50 printhead. The printheadwas purged and a control image was immediately generated. The printerwas allowed to sit idle for 30 seconds and then an image consisting of amatrix of individual dots representing single nozzle firings wasgenerated. The printer was allowed to sit idle for 1 minute and then aseries of images were generated. This line of testing was continued for3, 5, 10, 15, and 30 minutes. The results are presented in Table 5.

TABLE 5 Decap Test Results Idle time No. of drops fired before fullrecovery of jet (min) I-1 I-2 0.5 104 30 1 140 34 3 176 34 5 175 17 10189 — 15 — 9 30 248 4

Example 7 Inks with Intermediate Solvents

The inks of the formulations I-3 to I-5 (Table 6) can be preparedaccording to the method described in Example 1. Each column indicatesthe weight % of the ingredient in the final formulation.

TABLE 6 Inks with intermediate solvents Ingredient I-3 I-4 I-5 PMsolvent 72-80 72-80 72-80 Reactol K-3107 17-21 — — Alnovol PN430 — 17-21— Joncryl 682 — — 17-21 Orasol Black RLI 2-3 2-3 2-3 Zonyl FSO 100 0-30-3 0-3

Example 8 Inks with Slow Solvents

The inks of the formulation S-1 to S-4 (Table 7) were prepared accordingto the method described in Example 1. Each column indicates the weight %of the ingredient in the final formulation. The viscosity of the inks inTable 7 were measured using Brookfield DV Series Viscometer with a smallsample adapter at 40° C. using spindle 18 operating at 60 rpm spindlespeed.

TABLE 7 Inks with slow solvents Ingredient S-1 S-2 S-3 S-4 Dowanol TPMtripropylene glycol methyl 39 34.5 40.5 24 ether PigmentedConcentrate-2, (20.3% by weight 41 37 45 41 in TPM) Foral 85 solution(35% by weight in TPM) 20 27 13 20 Zonyl FSO100 0 1.5 1.5 — Surfynol 104(20% solution in TPM) — — — 15 Viscosity, cPs at 40° C. 11.7 11.6 12.311.8

Example 9 Inks with Slow Solvents

The inks of the formulation S-5 to S-12 (Table 8) were preparedaccording to the method described in Example 1. Each column indicatesthe weight % of the ingredient in the final formulation. The viscosityof the inks in Table 8 were measured using Brookfield DV SeriesViscometer with a small sample adapter at 40° C. using spindle 18operating at 60 rpm spindle speed.

TABLE 8 Inks with slow solvents Ingredient S-5 S-6 S-7 S-8 S-9 S-10 S-11S-12 Dowanol TPM 30.8 30.5 29.5 28.5 26 25.9 41.6 9 tripropylene glycolmethyl ether Joncryl 682 17 17 17 17 13.3 6.2 8.0 17 (acrylic copolymer)35% solution in TPM Pigmented 51.5 51.5 51.5 51.5 — — — — Concen-trate-1 Pigment — — — — 59.5 65.1 49 71 Concen- trate-2, (20.3% carbonblack in TPM) Zonyl FSO100 0.7 1 2 3 1.2 2.8 1.4 3 Viscosity, cPs 18.118.9 19.6 20.4 17 15.7 12.9 18.6 at 40° C. Ingredients are included asweight %

Example 10 Decap Test for the Slow Solvent Ink

The Markem-Imaje Model 5600 printer was loaded with the ink to betested. The system was purged and a test image, showing the properfunction of each nozzle, was made. This test image allows the user tovisually determine if any given nozzle is operating or not and if itsdirectionality and volume are proper. This jetting test was performed toassess initial nozzle function, then allowed the printer to sit idle.After a number of days (in this instance, either 1 day or 4 days), ajetting test was performed to assess the nozzle function; if fewernozzles were functional than in the initial jet test, an ink purge wasperformed. The nozzle performance was reassessed after each successivejet test until all of the original nozzles were functioning. The numberof purges required to recover all nozzles was recorded (Table 9).

TABLE 9 Decap Test Results number of purges No. of days S-1 S-2 1 1 0 44 0

Example 11 Inks with Slow Solvents

The inks of the formulation S-13 to S-16 (Table 10) can be preparedaccording to the method described in Example 1. Each column indicatesthe weight % of the ingredient in the final formulation.

TABLE 10 Inks with slow solvents Ingredient S-13 S-14 S-15 S-16 DowanolTPM tripropylene glycol 20-50 20-50 5-35 5-35 methyl ether PigmentedConcentrate-2, (20.3% 30-50 30-50 45-75  — by weight in TPM) PigmentedConcentrate-1 — — — 45-55  Foral 85 solution (35% by weight in 10-3510-35 — — TPM) Joncryl 682 (acrylic copolymer) 35% — — 5-20 5-20solution in TPM Zonyl FSO100 0-3 0-3  0-3.5  0-3.5 Surfynol 104 (20%solution in TPM) 0-3 0-3  0-3.5  0-3.5

Example 12 Alternate Decap Testing for Intermediate Solvents

Ink was loaded into a Dimatix Skywalker 128/50 printhead, the printheadwas purged and a control image consisting of 24 individual alpha numericcodes was immediately generated. The printer was allowed to sit idle for30 seconds and then an image consisting of 24 individual alpha numericcodes was generated. The number of times the codes had to be generatedto obtain both a legible code at arm's length (L*) and a perfect code(P*) was recorded. The printer was allowed to sit idle for 1 minute andthen an image consisting of 24 individual alpha numeric codes wasgenerated. This line of testing was continued for 3, 5, 10, 15, 60minutes and overnight. The results are presented in Table 11.

TABLE 11 Decap Test Results Idle time I-1 I-2 I-6 (min) L* P* L* P* L*P* 0.5 2 2 2 3 2 3 1 2 3 1 1 2 3 3 3 4 2 3 2 3 5 4 6 3 5 2 3 10 4 6 3 41 2 15 >24 >24 3 6 1 1 60 >24 >24 1 2 1 1 overnight >24 >24 2 2 1 1

A number of implementations have been described. Nevertheless, it willbe understood that various modifications can be made without departingfrom the spirit and scope of the disclosure. Accordingly, otherimplementations are within the scope of the following claims.

For example, while ethanol has been described for fast organic solvent,propanol or butanol can be used.

All of the features disclosed in this specification may be combined inany combination. Each feature disclosed in this specification may bereplace by an alternative feature serving the same, equivalent, orsimilar purpose. Thus, unless expressly stated otherwise, each featuredisclosed is only an example of a generic series of equivalent orsimilar features.

What is claimed is:
 1. An inkjet ink, comprising: a fast organicsolvent, a resin, a surfactant, and a colorant, wherein the ink is athermal inkjet ink, has a drying time of less than about 2 seconds, andhas a decap time of at least about one hour.
 2. The ink of claim 1,wherein the ink has a drying time of less than about 1 second.
 3. Theink of claim 1, wherein the ink has a decap time of at least about 10hours.
 4. The ink of claim 1, wherein the fast organic solvent isselected from the group consisting of methanol, ethanol, propanol,iso-propanol, acetone, methyl ethyl ketone, methyl isobutyl ketone,pentane, hexane, heptane, methyl acetate, ethyl acetate, propyl acetate,and combinations thereof.
 5. The ink of claim 1, wherein the fastorganic solvent is ethanol.
 6. The ink of claim 1, wherein the inkcomprises greater than about 90% of the fast organic solvent.
 7. The inkof claim 1, wherein the resin is selected from the group consisting ofrosin modified phenolic resin, phenolic resin, styrene-acrylic resin,polyketone resin, and combinations thereof.
 8. The ink of claim 1,wherein the surfactant comprises a fluorosurfactant, a siloxane-basedsurfactant, an acetylenic diol-based surfactant, a hydrocarbon-basedsurfactant, or a combination thereof.
 9. The ink of claim 8, wherein thesurfactant comprises a fluorosurfactant.
 10. The ink of claim 9, whereinthe fluorosurfactant is selected from the group consisting ofpolyethylene oxide-b-poly(tetrafluoroethylene)polymers,2-(perfluoroalkyl)ethyl stearate, anionic lithium carboxylatefluorosurfactant, anionic phosphate fluorosurfactant, anionic phosphatesurfactant, amphoteric quaternary ammonium-acetate fluorosurfactant, anda combination thereof.
 11. The ink of claim 10, wherein thefluorosurfactant is a poly(ethylene oxide)-b-poly(tetrafluoroethylene)copolymer.
 12. The ink of claim 1, wherein the surfactant is present inan amount of from about 1.1% to about 5% by weight of the ink.
 13. Theink of claim 1, wherein the ink comprises: greater than about 90% byweight of ethanol, a phenolic resin, from about 1.1% to about 5% byweight of the poly(ethylene oxide)-b-poly(tetrafluoroethylene)copolymer, and a colorant.
 14. The ink of claim 13, wherein the inkcomprises: 91.4% by weight of ethanol, 2.9% by weight of a phenolicresin, 2.0% by weight of the poly(ethyleneoxide)-b-poly(tetrafluoroethylene) copolymer, and 3.7% by weight of acolorant.
 15. An inkjet ink, consisting of: one fast organic solvent,one resin, one surfactant, and one colorant.
 16. The ink of claim 15,wherein the fast organic solvent is selected from the group consistingof methanol, ethanol, propanol, iso-propanol, acetone, methyl ethylketone, methyl isobutyl ketone, pentane, hexane, heptane, methylacetate, ethyl acetate, and propyl acetate.
 17. The ink of claim 16,wherein the fast organic solvent is ethanol.
 18. The ink of claim 15,wherein the ink consists of greater than about 90% by weight of the fastorganic solvent.
 19. The ink of claim 15, wherein the resin is selectedfrom the group consisting of rosin modified phenolic resin, phenolicresin, styrene-acrylic resin, and polyketone resin.
 20. The ink of claim15, wherein the surfactant is a fluorosurfactant, a siloxane-basedsurfactant, an acetylenic diol-based surfactant, or a hydrocarbon-basedsurfactant.
 21. The ink of claim 20, wherein the surfactant is afluorosurfactant.
 22. The ink of claim 21, wherein the fluorosurfactantis selected from the group consisting of polyethyleneoxide-b-poly(tetrafluoroethylene)polymers, 2-(perfluoroalkyl)ethylstearate, anionic lithium carboxylate fluorosurfactant, anionicphosphate fluorosurfactant, anionic phosphate surfactant, and amphotericquaternary ammonium-acetate fluorosurfactant.
 23. The ink of claim 22,wherein the fluorosurfactant is a poly(ethyleneoxide)-b-poly(tetrafluoroethylene) copolymer.
 24. The ink of claim 21,wherein the ink consists of from about 1.1% to about 5% by weight of thefluorosurfactant.
 25. The ink of claim 15, wherein the ink consists ofethanol, a phenolic resin, a poly(ethyleneoxide)-b-poly(tetrafluoroethylene) copolymer, and a colorant.
 26. Theink of claim 25, wherein the ink consists of: greater than about 90% byweight of ethanol, a phenolic resin, from about 1.1% to about 5% byweight of the poly(ethylene oxide)-b-poly(tetrafluoroethylene)copolymer, and a colorant.
 27. The ink of claim 25, wherein the inkconsists of: 91.4% by weight of ethanol, 2.9% by weight of a phenolicresin, 2.0% by weight of the poly(ethyleneoxide)-b-poly(tetrafluoroethylene) copolymer, and 3.7% by weight of acolorant.